Flexible, soft-covered books with stiff spines, such as telephone directories and catalogs, are difficult to store on shelves. Books with stiff spines but limp pages and covers slump or collapse when placed on ordinary book shelves so that they become misshapen, they are difficult to use, and they are unsightly. In fact, storing a number of such catalogs or directories on shelves is accomplished by stacking them flat, one upon another. However, books stacked upon one another are difficult to remove and replace.